Contact printer and paper drive therefor



Aug. 12, 1969 K. J. KALLENBERG 3,460,7

CONTACT PRINTER AND PAPER DRIVE THEREFOR Filed March 6, 1967 3 Sheets-Sheet 1 /6 *9 FILE-F2 .z n 7 7 N ---u- 27 24 22 I E D.C. SOURCE I N VEN'TOR. K424 I (Jae/V3526:

Arroamvrs 2, 1969 K. .1. KALLENBERG 3,460,732

CONTACT PRINTER AND PAPER DRIVE THEREFOR Filed March. 6, 1967 5 Sheets-Sheet 2 FIG 5:3

INVENTOR. K024 I A1uavat4 lrranm United States Patent Oiijce Patented Aug. 12, 1969 16 Claims ABSTRACT OF THE DISCLOSURE A contact printer including a paper feed mechanism having a feed roller and a paper takeup roller which exerts a constant tension on the paper as it moves across a platen used for supporting the paper in printing. The paper feed roller is driven with a friction tendency drive, and is normally latched against movement. Upon disabling of the latch, the roller will be driven, feeding the paper, and at the same time an element will be released and will rotate with the roller until the element contacts a switch to disable the feed roller. The positioning of the switch in relation to the number of degrees of rotation of the roller can be changed to provide variable feed.

BACKGROUND OF THE INVENTION Field of the invention The invention relates to contact printers for photographic negatives and more particularly to feed mechanisms that can be used on contact printers or on other devices wherein a precise measurement of the amount of feed of a rolled material such as paper stock can be obtained. Further, the invention pertains to the handling of such paper stock in a contact printer in order to avoid scratching the negative and in order to make the threading of the paper through the machine very easy.

Description of the prior art While there are several contact printers on the market, the problem of precisely adjustable paper feed has long been prevalent. The present device eliminates many of the problems involved in threading by having the paper feed pressure roller move with the cover of the machine so that whenever the cover is lifted, the pressure roller for the paper feed is removed. This makes the threading of the paper very easy. Further, the present device eliminates any loops in the paper which may cause the paper to rub against the negative as it moves across the platen during the paper feed cycle.

A further problem as solved by this device is the preciseness and high speed operation that can be achieved with the paper feed selecting mechanism so that a precise length of paper can be fed and the paper feed can be repeated rapidly.

In all photographic printing equipment wherein a continuous web of light sensitive material is utilized, it is necessary to intermittently expose a length of this material to an image forming light, and then transport this lengh away from the exposure area while a fresh length is moved into this exposure area. Since there are a number of format or finished print sizes in practice, it is desirable to be able to pre-select a transport length. The standard format length are in some multiple of half inches, and while some other increment may be suitable, the feed increments of the device disclosed is in half inch steps.

SUMMARY The present invention therefore enables the precise feeding of measured lengths of sheet material such as paper from a storage roll at very rapid intervals. The changing of the length of material fed is also very precise and simple to do. Simple feeding, with no scratching of the negative being printed, and very accurate measurements of lengths of paper are some of the objects that are achieved with the present invention. Further, the ease of threading the paper is enhanced with the present device.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic cross sectional view of a contact printer made according to the present invention;

FIGURE 2 is a perspective view of the contact printer made according to the present invention shown with a cover raised for threading paper in place;

FIGURE 2A is a sectional view of a paper takeup roller showing a typical friction tendency drive for the roller;

FIGURE 3 is a fragmentary enlarged elevational view of the paper feed mechanism used with the device of FIG- URE 2;

FIGURE 4 is a sectional view taken as on line 4--4 in FIGURE 3;

FIGURE 5 is a fragmentary sectional view taken as on line 55 in FIGURE 3;

FIGURE 6 is a fragmentary sectional view taken as on line 66 in FIGURE 3;

FIGURE 7 is a fragmentary enlarged sectional view taken as on line 7-7 in FIGURE 6;

FIGURE 8 is a fragmentary sectional view taken as on line 88 in FIGURE 7;

FIGURE 9 is a fragmentary enlarged sectional view showing the detail of a cam and roller one-Way clutch drive utilized for driving the pulleys shown in FIGURE 6 and partially broken away in FIGURE 6; and

FIGURE 10 is a schematic representation of the electrical controls utilized with the paper feed mechanism of FIGURE 3.

Referring to the drawings and the numerals of reference thereon, a contact printer illustrated generally at 10 includes a cabinet 11 mounted on a pair of legs 12. The cabinet serves as a main frame and houses all of the components for the printer. At the top of the cabinet is a light box or lamp house 13. The lamp house is hingedly connected to a top cover 14 of the cabinet about a hinge axis that is transverse to the cabinet and is positioned just at the top of the cabinet, along axis 15. The lamp house can be folded back upon the cover and has a light source 16 which is controlled through a timer and switch, schematically shown for manual initiation. Under automatic operation the light will automatically be turned on at the proper time, after the paper Web on which the print is to be made has been positioned properly. The light will be on for the proper preselected exposure time, and then will automatically shut off while the machine goes through its complete cycle.

The lamp house has suitable guides for holding a glass plate 17 that can be masked in a suitable manner and used for mounting a negative 18 from which a contact print is to be made. The negative is mounted on the bottom side of the glass plate and positioned above and aligned with a vertically reciprocal platen 21. The platen can be moved back and forth in vertical direction with many different mechanisms. However, as shown schematically in FIGURE 1, the platen support rests on top of a roller carriage 28. The carriage 28 moves up and down in an arc, but because of the roller carriage and the provision suitable guides, the platen will move vertically toward and away from the plate 17. The roller carriage is actuated from two arms 29 (one on each side) pivotal- 1y mounted to the carrage and each of the arms is driven by an output shaft of a separate rotary solenoid 30. The solenoids, when energized, rotate their output shafts in direction as indicated by the arrow in FIGURE 1 and when released a spring load returns the platen to its original position.

The energization of solenoids 30 moves the platen from its rest position shown in FKGURE 1 (spaced from negative 18) to position wherein it will force a web or strip of light sensitive paper 22 passing over the platen up against the negative 18 so that the paper and negative are in intimate contact. The top portion of the platen is covered with a soft rubberlike material and will tightly clamp the paper against the negative to eliminate any air bubbles which cause imperfections in the print made on the paper after exposure. The solenoids 30 that actuate the platen are electrically connected to actuate the platen at the proper time in the operational sequence for the machine. However, again strict manual operation is shown schematically for purposes of illustration. These rotatary solenoids are available commercially.

The paper strip or web 22 is threaded through the machine and comes from a supply roll 23 mounted on a mandrel that is rotatably mounted with respect to the cabinet in a conventional manner. The paper can be any desired width so that the proper size paper is available for the negative being printed. The strip of paper 22 passes over a first idler roller 24 that is rotatably mountted in the housing or cabinet and then down around a stripper roller 25 that is rotatably mounted onto a pair of arms 26 positioned on opposite end of the roller. The arms in turn are pivotally mounted with respect to the cabinet about the same axis as the axis for paper roll 23 and will swing about this axis. The arms are spring loaded so that they will take up the shock loads from sudden starting and stopping of the paper drive. The paper then passes up over a second idler roller 27 which is also rotatably mounted in the cabinet and has guide washers between which the strip is placed.

The paper strip 22 then passes between a transfer roller 33 and a pressure roller 34. The transfer roller 33 is rotatably mounted in suitable guides on opposite sides thereof. The transfer roller 33 is a rubber covered roller and rides in contact against the surface of paper drive wheels 35 and transfers any rotary motion of the drive wheels through the transfer roller to the paper strip 22 positioned between the transfer roller and the pressure roller.

The pressure roller 34 is mounted in a unique manner to simplify the threading of the machine when it is initially started. As can be seen, the pressure roller 34 is rotatably mounted in bracket 38 that has arms on opposite sides of the roller and this bracket in turn is pivotally mounted onto other brackets 39 that are fastened to the cover 14 of the cabinet. Spring means 41 is provided for urging the bracket 38 and roller 34 downwardly away from the cover. The bracket 38 is made so its pivotal movement is stopped to prevent it from traveling too far when the cover 14 is open. When the cover is raised about its hinge axis 46, the pressure roller 34 is carried with the cover up away from the transfer roller 33. The paper is not then pinched between the pressure roller and the transfer roller and the strip can easily be threaded over the transfer roller, over the platen and onto the paper takeup assembly without the necessity for separately releasing the pressure on the pressure roller. Then when the cover is placed back into place and latched with suitable over-center clamps 37, the pressure roller pinches the paper between it and the transfer roller under pressure of spring 41. This in turn resiliently forces the transfer roller down against the paper drive wheels so that any movement of the drive wheels is transmitted directly through the paper and causes the paper to move. The pressure roll thus provides the friction force to effect a drive from wheels 35. Note that the shaft for roller 33 does not bottom in the slots used for mounting it, so the spring force from roller 34 acts against the paper and down onto the wheels 35 (see FIGURE 4).

After the paper web or strip 22 has moved across the platen 21 the strip is threaded over an upper takeup roller 42 that is rotatably mounted with respect to the cabinet and is driven through a belt 43 driving through a pulley arrangement from a motor 44. The takeup roller 42 has a section that is rubber covered and engages the paper strip. The roller 42 is driven through a conventional friction tendency drive as shown that will permit the roller to slip whenever the paper is not feeding. The drive belt 43 continuously drives. The friction tendency drive is an internal friction clutch assembly that keeps a constant driving force on the roller, and thus on the paper.

As shown in FIGURE 2A the friction tendency drive is between a shaft rotatably mounted within the roller 42 and a disc 48 that is fixed to the roller body with screws. The shaft drives the disc through two pressure plates 50 that are rotationally drivably slidably mounted on the shaft. The plates 50 sandwich two oiled felt discs 49 that bear against disc 48. A spring takeup 51 provides the clamping force to get the drive between discs 50 and disc 48. This drive slips constantly when the paper is not being fed.

A spring loaded takeup pressure roller 45 clamps the strip 22 against the takeup roller 42. The pressure roller 45 is spring loaded against the takeup roller. The paper strip 22 then passes over a foam covered cushion roller 46 that is mounted on arms 47 that are pivoted to the cabinet. The foam cushion roller is spring loaded to absorb the inertial load from a paper takeup spool 52. A lower takeup roller 53 drives the takeup spool through surface friction contact. The roller 53 is driven through belt 54 and suitable pulleys from the motor 44 and uses a friction tendency drive like that of roller 42. Thus the printed paper is added on the takeup spool, and once the run is completed the takeup spool would then be removed.

The relationship between the speed of the takeup roller 42 and the speed of the paper drive or paper feed wheels is such that the takeup roller 42 has a higher linear peripheral speed than the paper drive wheels. The paper strip 22 is thus under tension at all times (limited by the friction tendency drive of the upper takeup roller) as it passes over the platen. Thus, when the platen is released or drops down from the negative and the paper advances, the paper is held tightly against the upper surface of the platen and will not loop up and scratch the negative. The top surface of the platen is raised slightly from the tangent plane which passes across the tops of rollers 33 and 42. This means that the paper strip is held tightly on the surface by the faster takeup drive. The negative will not be damaged by paper scratches even in long runs where a large number of contact prints are being made from the same negative.

The cabinet is light tight, so that once the unit is loaded and automatically set to run repeat cycles, the machine can operate in light. The cover 14 is sealed to prevent light leaks, and the ends of the cabinet are closed by flexible sliding doors 55 made of black synthet ic material and riding in tracks 56 on opposite sides of the cabinet. There is a door 55 at each end of the cabinet. These doors can be opened for ease of loading and slid closed against to make the unit light tight. The tracks 56 are at least /2 inch deep to block light.

A control housing 57 is used for mounting switches and other control components. This can also be swung out about a bottom hinge for easy servicing.

Referring specifically to FIGURES 3 through 10 showing the paper drive metering wheels and the detail of the paper metering drive, it should be noted that there is a constant tension on the paper Web from takeup roller 42. While the paper metering drive is in fact the feed mechanism, for feeding paper from roll 23 it also acts as a brake when stopped to hold the web from moving. In this respect it is a metering device as well. The drive wheels 35 comprise a pair of flanged disc that are drivably mounted onto a shaft 60. The shaft 60 is rotatably mounted at one end in a bearing 61 that is mounted in turn onto a support attached to the frame for the machine. The shaft is also mounted in a second bearing 62 that is in turn mounted onto a suitable sup port. The shaft 60 extends outwardly beyond the hearing a substantial distance.

As stated previously, the paper drive wheels 35 are flanged discs and the flanges comprise the periphery of the Wheel. The outer periphery of these wheels are covered with a suitable rubber material 63 which has high friction properties. The wheels 35 are spaced apart on the shaft as shown. Between the wheels 35 there is p0- sitioned a latch mechanism or assembly 65. Also, there is a rachet wheel 66 that is suitable drivably mounted on the shaft 60. The ratchet wheel 66 has 48 equally spaced ratchet teeth 67. The outer periphery of the paper drive wheels 35 corresponds to twenty-four inches of paper feed. Thus each of the ratchet teeth 67 corresponds to a distance of one-half inch of paper feed. The latch assembly 65 includes a latch dog 68 that is drivably mounted in a suitable bearing housing 70 that is mounted to the frame with members 71. The shaft 69 is drivably coupled to an output shaft 73 of a rotary solenoid 74. The rotary solenoid '74 is of conventional design and when the solenoid is energized, the output shaft 73 will rotate a predetermined number of degrees. A stop 72 engages the latch dog to prevent over travel. The solenoid in turn is also mounted onto an upright member 75 attached to the frame of the machine. One member 71 is attached to member 75.

When the solenoid 74 is energized, it will rotate its output shaft, thus rotating the shaft 69 and moving the latch dog 68 to position as shown in dotted lines in FIGURE 4, clearing the teeth 67 of the ratchet wheel. When the dog is removed from the ratchet teeth, the shaft 60 can rotate (the drive motor is always running during operation) until the latch dog 68 is dropped back into place and then again engages one of the ratchet teeth. As shown, a spring 76 urges the dog toward the ratchet teeth.

The shaft 60 is driven through a slip clutch or friction tendency drive assembly illustrated generally at 80 (see FIGURES 3 and S). The slip clutch or friction tendency drive assembly 80 includes a tubular hub member 81 that is drivably mounted onto the shaft 60 and surrounds the shaft.

The hub member can be driven with a roll pin 82 passing through the hub and the shaft. In order to provide for the friction tendency drive, a spring retaining ring 83 is snapped into a provided groove of the hub 81 and retain a backup plate 84 on the hub. Then, a frictional driving disc 85 which as shown is comprised of an oiled felt is placed against the backing plate. A hearing 86 is mounted on the shaft and held between two snap rings 87, which are positioned in grooves in the hub. A sprocket 90 is rotatably mounted on the bearing 86 so that it can turn with respect to the hub and also will slide in axial direction on the hearing. The disc 85 is positioned between the side of the sprocket 90 and the backup plate 84. A center opening in the disc fits over the hearing.

A second disc 91 also comprises oiled felt and is positioned against the side of the sprocket opposite from disc 85 and is slidably mounted over the bearing 86. A pressure plate 92 .is then placed against the disc 91 and a spring end washer 93 is backed against the pressure plate. A spring 94 is mounted over the hub, and mounts onto the spring end washer 93. Further, the opposite end of the spring is held by a nut 95 threadbly mounted over the hub and shouldered to guide the spring. By adjusting the nut 95, the pressure with which the spring bears against the pressure plate can be changed. This then provides for adjustment of the torque that can be carried by the sprocket. The sprocket will slip whenever the latch dog engages one of the ratchet teeth on the ratchet mechanism. The sprocket and discs are made so that they will stand extended periods of slippage without grabbing or failing to operate satisfactorily. The discs and 84 are rotationally driven with hub 81 by a flattened portion of the hub mating with the apertures in discs 80 and 84. This permits the discs to axially slide for torque adjustment.

The sprocket 91) is driven through a chain 96 from a second sprocket 97 that in turn is drivably mounted into an output shaft 102 of a motor 103 that is mounted with respect to the frame of the machine below the paper feed mechanism. A chain tightener 104 may be provided to obtain proper chain tension. Thus Whenever the motor 103 is running (it is on all the time when the machine is used) the chain 96 will be driven and this in turn will drive the sprocket 90. If the latch dog 63 is against a ratchet tooth, the sprocket will slip and will thus give a frictional tendency to rotate shaft 60. Whenever the solenoid 74 is energized, it will release the latch dog 63 from the engaged tooth 67 and permit the ratchet wheel 66, shaft 60 and the paper drive wheels 35 to rotate. The frictional contact between the rubber surface of the paper drive wheels 35 and the transfer roller 33 will cause the roller 33 to rotate. The paper clamped between the transfer roller 33 and the pressure roller will be driven and removed from roll 23 until the solenoid 74 is released permitting the dog again to engage the ratchet teeth and stop the feed shaft 61}.

Adjacent to the outer end of the shaft 60, and neXt to the friction tendency drive assembly 80, there is a paper feed shut off control. This assembly is illustrated generally at 163 and includes a number of components. Some of the components are not directly connected to the shaft 60 but work in conjunction with it.

A magnet carrying wheel 109 has an integral pulley 110 at one edge thereof. The magnet wheel is in turn mounted onto a self-contained one way clutch assembly 112 which drives the wheel from the shaft 61) in one direction and free wheels, or permits rotation of the wheel with respect to shaft 61} if the differential motion is in the opposite direction. This type of one way clutch is a conventional item commonly comprising rollers 111 held .in a cam housing 113 and contacting the shaft 60. The cam housing 113 has several cam pockets that each house a roller and a small spring which will urge the rollers up the cam ramps of each pocket. When the pulley and magnet wheel are rotated in direction as indicated by the arrow 114 (FIGURE 9) and the shaft 60 is stopped, the magnet wheel will free wheel or will not tend to drive to the shaft 61). However, when the shaft 60 is rotated in this same direction at a rate faster than the rotation of the magnet wheel, the shaft 641 will drive the magnet wheel and pulley because the rollers will cam against the shaft and the cam ramps and effect the driving connection. The cam and roller drive shown is a conventional one, such as Series RCB made by the Torrington Bearing Company of Torrington, Conn. Bearings are provided in the housing to support the wheel when it free wheels. A belt 115 is drivably mounted onto the pulley 110 and in turn is drivably mounted onto a second pulley 116 mounted through another cam and roller one way clutch assembly 117 to the output shaft 102 of motor 103. The cam and roller one way clutch 117 is made exactly like the one between the pulley 110 and shaft 613. The cam roller 117 will drive when shaft 102 is driven in direction as indicated by arrow 118 and will free wheel if the pulley goes faster than the shaft in this direction. The clutches are selected so that when the shaft 611 is not rotated, the cam and roller one Way clutch 117 will drive pulley 116 thus driving the belt 115 and in turn driving pulley 110. This will cause the magnet wheel 109 to rotate in direction as indicated by arrow 114 and because the shaft 611 is stationary the clutch 112 between the pulley 111) and shaft 61) will overrun or free wheel. When the shaft 60 starts to rotate at a rate faster than the pulley 110 is rotating, then the wheel 109 will be driven by clutch 112 and belt 115 in turn will drive pulley 116 at faster rate than shaft 102 and cause the cam and roller 117 to free wheel or overrun. The use of two overrunning 7 one way drive clutches permits driving the wheel 109 at all times. When the shaft 60 is held, the wheel 109 is driven by belt 115 from the motor 103. However, when the paper feed is started and chain 96 drives shaft 60, the shaft travels faster and drives wheel 109 at the same rate.

A plurality of tripping magnet assemblies 125 ar mounted onto the peripheral rim portion of the magnet wheel 109. As shown (FIGURES 6, 7 and 8), three such magnet assemblies are mounted thereon. Each of the magnet tripping assemblies comprises an outer nylon or other low friction material housing 126 each of which has grooves defined therein to form spaced legs 127. The legs are positioned in opposite sides of the rim of the magnet wheel and prevent the magnet assemblies from going transversely to the plane of the wheel and falling off the wheel. An annular groove 124 is defined in one side of the rim and the adjacent leg 127 has a pin 128 therein that protrudes into the groove slightly. This aids in keeping the assemblies from coming off the rim, but the assembly can be cocked and removed manually. The nylon housings have arcuate internal surfaces 129 (at the base of the groove which defines legs 127) that ride against the peripheral surface 130 of the wheel rim. Each of the nylon housings holds a permanent magnet 131. The magnet is on the opposite side of a wall 132 from the surface 129 so that it does not actually touch the peripheral surface 130 of the magnet wheel. However, the magnet Wheel 109 is made of a magnetic material and th force of the magnet 131 is sufiicient to hold the magnet tripping assemblies 125 inwardly against the surface 130. This means that there is always contact between the surface 129 of the nylon housings and the peripheral surface 130 of the magnet Wheel. An integral lug 133 extends outwardly from the housings in direction away from wheel 109. A suitable adhesive holds the magnets in the housings.

The magnetic force between the magnet carried by each of the assemblies and the magnet wheel causes the magnets to tend to rotate with the wheel. A magnet tripping assembly release rotary solenoid 135 is mounted onto the frame of the machine and has an output shaft 136 that mounts an arm 137. The arm 137 is positioned so that when the magnet tripping assembly release solenoid is relaxed or not energized, the arm intercepts the normal path of travel of the lugs 133 of the magnet tripping assemblies as they are carried by the magnet wheel. The arm prevents the assembly it contacts from rotating with the magnet wheel. When an assembly is stopped in this position the magnets will still have sulficient force to hold the surfaces 120 and 130 together, but there will be slippage between the surfaces 129 and 130 whenever the magnet wheel rotates. When three magnet tripping assemblies are on the wheel as shown, all three slip when the arm 137 holds the first one. When the magnet release solenoid is energized, its shaft 136 will rotate a sufficient distance so the arm 137 will move to release position as shown in dotted lines in FIGURE 3, out of its interferring position with lug 133 and permit the magnet tripping assemblies to move with wheel 109. It should be noted that the magnet release solenoid is a pulse type solenoid operating on a capacitor discharge and only momentarily energizes to flick the arm out of the path of travel of the lug 133 and then is spring loaded to return to its original position. As soon as it is released, the lug 133 will rotate with the wheel 109 past the plane of movement of the arm. When the arm 137 moves back to its original position, the leading magnet tripping assembly will continue to travel with the wheel. The magnet tripping assembly following the released magnet tripping assembly will be stopped by the arm 137 and held until the solenoid 135 is again reset and triggered. Only one magnet tripping assembly will be released each time the solenoid 135 is energized.

The device is interlocked so that solenoids 135 and latch solenoid 74 are energized at the same time. Thus, when anyone of the magnet tripping assemblies 125 is released, the paper drive wheels will be released and paper will be fed. Shaft 60 will rotate. The released magnet tripping assembly will be carried by the magnetic force between magnets 131 and the magnet wheel 109, along with the wheel. In its path of travel as the wheel rotates, the outer side surface of the assembly (the side away from the pulley is of size so that it will intercept and actuate the finger (which has a roller end) 140 of a micro-switch 141. The switch 141 is used to shut OH? or deenergize the latch solenoid 74 and stop the drive of the paper feeding mechanism.

After the paper drive has stopped, the wheel 109 Will then be rotated by belt 115 and will carry the released magnet assembly (tripping device) to its home position. Using three magnet assemblies permits recycling the paper feed before the previously released magnet has reached the home position. For short paper feed and short exposures the machine will cycle very rapidly.

The switch 141 is mounted onto the outer end of an arm 142 that in turn is clamped onto a shaft 143. The clamping is made so that the arm' can be adjusted with respect to the shaft 143 if desired and reclamped in place. In operation the arm moves with the shaft. The shaft 143 in turn is rotatably mounted in a suitable housing 144 that is attached to the side wall of the cabinet for the machine. The shaft 143 passes through the side Wall of the machine to the exterior thereof.

A spring 145 is mounted over the housing 144 and engages the arm 142 and urges the shaft and arm longitudinally in direction as indicated by arrow 14 9. On the outside of the cabinet a disc 146 is fixedly attached to the shaft so that it will not slide longitudinally with respect to the shaft. The disc rotates with the shaft. Thrust washers may be provided between the disc and the cabinet. A control or metering index knob 148 is drivably mounted to the outer end of the shaft 143. The index knob can be gripped, pulled in direction opposite that indicated by arrow 149 and this in turn will move the shaft and release the disc 146 from a small peg 150 that is fixed to and protrudes from the cabinet. The peg 150 is adapted to align with and fit into one of a plurality of holes 151 in the disc 146. Once the peg 150 is released from the holes, the shaft 143 can be rotated, and this in turn will rotate arm 142. The rotation of the arm 142 moves the microswitch and changes its angular position with respect to the home position of the magnet tripping assemblies. The are that a magnet assembly released by the solenoid 135 has to travel before contacting and actuating switch 141 can be varied. This means that the number of degrees that the paper drive wheels will travel after the solenoid 74 and the solenoid 135 have been energized (they are energized together) and before one of the magnet tripping assemblies trips micro-switch 141 to de-energize solenoid 74 and let the latch dog engage the ratchet wheel can be changed. For example, if the arm 142 and switch 141 are rotated to position as shown in dotted lines in FIG- URE 6, the switch would be opened a shorter time after the assemblies 125 were released and only a short section of paper would be fed. It follows, of course, the number of degrees of rotation of the shaft 60 determines the distance that the paper web or strip 22 will be driven.

The drive for wheel 109 from motor 103 will rotate wheel 109 until shaft 60 is rotating, at which time shaft 60 will drive the wheel so it rotates the same amount of arc as the paper drive wheels. Once the shaft 60 is again stopped the slower drive from motor 103 will continuously rotate wheel 109 to return the released magnet assemblies to their home positions.

The controls for the various components of the machine are shown very schematically, except for the interlock of the feeding mechanism. The unit can be made to operate completely automatically and various interlocks, timing devices and other switches will be used. However, for sake of illustration here, motors 44 and 103 are shown to operate off the same switch so that when the main power is on, both motors will be constantly running. The

solenoids 30 for operating the platen also are shown to operate off a separate manual switch which will press the paper up against the negative. The light 16 is operated through a switch and a timer so that the proper timing of the exposure will be made. The platen will be released and dropped down after exposure and before the paper is advanced. It is to be understood that various interlock switches would be used for automatic operation of the device.

The motor 103 and 44 are running continuously during operation of the machine, so the only thing necessary to control paper feed is to release latch 68.

Referring specifically to FIGURE 10, a schematic representation of the paper feed and metering circuit is shown. This circuit as shown operates from a 150 volt DC source. In order to initiate the paper drive, a start switch 155 is depressed or closed either automatically or manually and this then energizes a relay coil 156 which causes normally closed contacts 157 to open and normally open contacts 158 to close, to complete a circuit across power through a resistor 159 and a capacitor 160. This will charge the capacitor 160. Also, energization of relay coil 156 causes normally closed contacts 161 to open and normally open contacts 162 to close. The closed positions of contacts 158 and 162 are shown in dotted lines. The closing of contacts 162 completes a circuit through a resistor i163 and a capacitor 164 to charge this capacitor. Then the start switch 155 is released and opened. (This will be done either manually or automatically.) This will relax the relay coil 156 and cause the normally closed contact 157 to close. The capacitor 160 will then discharge through resistor 159 to energize the magnet release solenoid 135. The time of discharge of the capacitor 160 is determined by the values of the capacitor and the resistor 159. The arm 137 is moved to released position when solenoid 135 is energized. At the same time, normally closed contacts 161 will close again, and capacitor 164 will discharge through resistor 163 and will energize a relay coil 165. This relay coil 165 closes normally open contacts 166 and completes a lock on circuit across the power lines through normally closed switch 141 to the coil 165. Also, normally open contacts 167 will close and this will energize latch solenoid 74 releasing dog 68 and permitting the drive wheels 35 to rotate.

As it can be seen, the latch solenoid is thus locked on as long as relay coil 165 is locked on. The on position of the latch solenoid is a latch released position so the shaft 60 is rotating. The magnetic assembly release solenoid 135 was actuated for only the length of time that it took the capacitor 160 to discharge, but during this time the arm 137 had moved to permit one of the magnet tripping assemblies to be carried by the magnet wheel 109. Then when the magnet wheel has traveled sufficiently far so the released magnet tripping assembly intercepts the switch (141, this switch 141 is opened. As can be seen from the schematic diagram of FIGURE 10, opening switch 141 will break the lock on circuit to relay coil 165, relaxing that relay and permitting contacts 166 and 167 to open. This means that the latch solenoid will relax, dropping the latch into place so that the latch dog will engage the next tooth on the ratchet wheel, and the feed mechanism will be stopped at the precise position where it is supposed to stop.

Thus the energization of solenoid 74 and solenoid 135 occurs upon the release of switch 155, and they will not be energized until switch 155 has been closed, to charge capacitors 160 and 164 and released again to permit these capacitors to energize the solenoid 135 and the latch control relay coil :165.

I claim:

1. A mechanism for feeding preselected lengths of strip material comprising a supply of material in strip form, a continuously urging strip drive means for removing said strip of material from said supply, latch means for stopping and holding said drive means to prevent said drive means from removing said strip from said supply, actuating means for disengaging said latch means, and control means including an element, first means carrying said element and being movable with said strip drive means, second means continuously urging said element to move with said first means, and means to restrain movement of said element with the first means and to release said element upon the disengagement of said latch means and adjustably positioned disabling means cooperating with said element so that during the operation of said drive means said element causes said disabling means to disable the actuating means for said latch means thereby permitting said latch means to stop said drive means.

2. A mechanism for feeding preselected lengths of strip material comprising a supply of material in strip form, a continuously urging strip drive means for removing said strip material from said supply, latch means for stopping and holding said drive means to prevent said drive means from removing said strip from said supply, actuating means for disabling said latch means, and control means including an element, an element carrying member, means to move said element carrying member in a predetermined relationship with said drive means when the drive means is removing said strip from said supply, means providing magnetic force between the element and the element carrying member tending to carry the element along with said element carrying member, and adjustably positioned disabling means cooperating with said element so that during the operation of said drive means said element causes said disabling means to disable the actuating means for said latch means thereby permitting said latch means to stop said drive means.

3. The mechanism as specified in claim 2 and means to normally restrain said element for movement with said element carrying member at a home position and to release said element to permit movement thereof with said element carrying member upon disabling of said latch means.

4. The combination as specified in claim 3 and means to move said element to its home position after it has caused said disabling means to disable said actuating means.

5. The mechanism of claim 2 wherein said element carrying member moves in a closed path of travel and said disabling means is movable in a path of travel substantially parallel to the path of travel of said element carrying member, and adjustable stop means to hold said disabling means at predetermined positions along its path of travel.

6. The mechanism specified in claim 2 and one way drive overrunning clutch means between. said element carrying member and said strip drive means, and second drive means to drive said element carrying member in its path of travel when the latch means is engaged and at a slower rate than the strip drive means, said one way drive overrunning clutch means slipping when the strip drive means is held by said latch means.

7. A mechanism for controlling feed of material in strip form comprising a frame, a supply of material in strip form, a first shaft rotatably mounted. on the frame adjacent said supply of material, a feed wheel drivably mounted on said first shaft, means for providing a frictional drive between said strip and said] wheel, drive means for said first shaft including a slippage element which will permit said first shaft to be held from rotation but will exert a driving force thereon, latch means for normally holding said shaft from rotation, actuating means for disengaging said latch means, a control wheel mounted on said shaft means, first one way clutch means between said shaft means and said control wheel and oriented so that when said shaft means is rotated by its drive means at a rate faster than said control wheel said first one way clutch means will drive said control wheel, a motor having an output shaft, means to drive said motor during operation of said mechanism, a driving member on said output shaft, said driving member being connected to said output shaft through second one way clutch means for driving said driving member when the motor shaft is rotating, means between said driving member and said control wheel to cause said control wheel to rotate in the same direction as said first shaft but at a slower rate than the first shaft rotates when the latch means is disengaged, said second one way clutch means permitting said driving member to overrun said motor shaft when the control wheel on said first shaft is driven by said first shaft means, an element slidably mounted on said control wheel, means urging said element to move with said wheel, disabling means positioned adjacent said control wheel and in the path of travel of a portion of said element when it moves with said wheel, and movable stop means for normally holding said element in a home position and preventing it from moving with said wheel and operative to release said element, said movable stop means and said actuating means being operative substantially simultaneously, and said disabling means being operative to disable said actuating means upon being contacted by said element to permit the latch means to return to its normal position.

8. The mechanism of claim 7 wherein the strip is a light sensitive paper strip used for making prints in a contact printer, including a frame mounting said mechanism, a platen for supporting said strip for exposure after it has passed said feed wheel, strip takeup means for receiving the strip from said platen after it has passed said platen, and friction drive means constantly urging said strip takeup means to takeup said strip at a rate faster than said feed wheel feeds said strip, said feed wheel restraining said strip against the urging of said strip takeup means.

9. The contact printer of claim 8 wherein the drive means for said first shaft and said friction drive means for the strip takeup means include separate electric motors, and control means to operate said electric motors at the same time.

10. The combination as specified in claim 7 wherein said elements comprises a housing slidably mounted on the periphery of said control wheel, and magnetic force supplying means between the element and the periphery of the control wheel to urge said element to travel with said control wheel.

11. The mechanism of claim 10 wherein the means to provide magnetic force comprises a permanent magnet in said housing, and said control wheel is of magnetic material.

12. The mechanism specified in claim 7 and a rotatable control shaft coaxial with said first shaft, an arm mounted on said control shaft and movable with said control shaft in a plane substantially parallel to the plane of said control wheel, said disabling means being positioned on said arm, and detent means for holding said shaft in one of a plurality of angular positions with respect to the home position of said element.

13. The mechanism specified in claim 7 wherein the actuating means and movable stop means comprise separate solenoid operated devices, and means to operate said solenoids substantially simultaneously.

14. The mechanism specified in claim 13 wherein said disabling means comprises a switch which opens the circuit to the actuating means solenoid when said switch is contacted by said element.

1 5. In an automatic contact printing machine for sequentially making a plurality of contact prints on a continuous strip of paper from a single negative, and having a paper strip supply and feeding means, a platen positioned to receive said strip of paper from said feeding means and support said paper for printing an image from the negative, and a paper takeup mechanism for receiving the paper strip from said platen, said feeding means controlling movement of said strip across said platen, the improvement comprising means to exert a force tending to drive said paper takeup means at a rate faster than said paper feeding means supplies paper from said supply, thereby tensioning the portion of said paper strip supported by said platen, said paper feeding means including a roller supporting said paper adjacent and spaced from a first edge of said platen, and said paper takeup means includes a roller supporting said paper adjacent and spaced from a second end of said platen, said platen defining a plane above a tangent line extending between said rollers for supporting said paper strip whenever the paper strip is advanced by said paper feeding means.

16. The printing machine of claim 15 and means to move said platen to position with the paper strip contiguous to said negative for printing and to move said platen to a second position with the paper clearing said negative when the paper strip is advanced.

References Cited UNITED STATES PATENTS 2,658,751 11/1953 Jaeschke 226 X 2,809,582 10/1957 Crawford 226-195 X 3,163,342 12/1964 Kallenberg 226l41 3,207,400 9/1965 Halberg 226-136' M. HENSON WOOD, IR., Primary Examiner R. A. SCHACHER, Assistant Examiner US. Cl. X.R. 

